Method for calculating active power loss of power grid caused by automatic voltage control based on sensitivity

Abstract

The invention provides a method for calculating power grid active loss caused by automatic voltage control based on sensitivity, and belongs to the technical field of power system voltage control. The method comprises the following steps: when a current automatic voltage control cycle arrives, obtaining a reactive power equipment set influencing the active power loss of the power grid and calculating the sensitivity of reactive power output of each reactive power equipment in the set to the active power flow loss of the power grid; calculating the active power flow loss of the power grid caused by the reactive power equipment in combination with the reactive power output variable quantity of the reactive power equipment in the current automatic voltage control period; and based on the power grid active power flow loss caused by the reactive equipment, performing integration by adopting a rectangular method to obtain the power grid active power loss caused by the reactive equipment. According to the method, the quantitative calculation result of the active loss of the power grid caused by automatic voltage control after the automatic voltage control system is put into closed-loop operation can be obtained online in real time, and safe and efficient operation of the power grid is facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of power system voltage control, and in particular relates to a method for calculating active power loss caused by automatic voltage control based on sensitivity calculation. Background Art

[0002] Automatic Voltage Control (AVC) systems are a key means of ensuring safe (improving voltage stability margin), economical (reducing network losses), and high-quality (improving voltage compliance) operation of transmission networks. Built on the grid's energy management system (EMS), the AVC system leverages real-time transmission network operational data to scientifically determine the optimal reactive power and voltage adjustment plan from a global perspective. These plans are then automatically distributed to power plants, substations, and lower-level grid dispatching organizations for implementation.

[0003] Sun Hongbin, Zhang Boming, and Guo Qinglai describe the architecture of large-scale automatic voltage control (AVC) in "Design of a Global Voltage Optimization Control System Based on Soft Partitioning" (Automation of Electric Power Systems, Vol. 27, No. 8, 2003, pp. 16-20). The master station portion of the AVC system is implemented in software within the power system control center. Its voltage control strategies for the transmission network primarily fall into two categories: reactive power control for each generator in the power plant and reactive power control for substations. The current primary approach for reactive power control for each generator in the power plant is as follows: the AVC master station system at the dispatching center calculates reactive power regulation for each unit in the power plant through reactive power optimization and transmits this information to the AVC substation system within the power plant via a data communication channel. Upon receiving the reactive power regulation, the AVC substation adjusts the reactive power output of each generator in a stepwise manner based on the current operating status of each generator within the power plant until the reactive power reaches the regulation value issued by the AVC master station. Substation control involves switching commands for reactive power compensation equipment and adjusting the transformer's on-load tap changer. Reactive power devices primarily include capacitors and reactors. When capacitors are switched on or reactors are switched off, the bus voltage increases; when capacitors are switched off or reactors are switched on, the bus voltage decreases. Transformer on-load tap changers are typically mounted on the transformer's high-voltage winding. Raising the tap position increases the medium- and low-voltage bus voltages, while lowering the tap position decreases them. The AVC master station issues commands to switch reactive power on or off, as well as to raise or lower the taps. The substation's automated monitoring system responds to these commands, switching reactive power devices or adjusting the taps within the substation.

[0004] During the transmission and distribution of electrical energy, a certain amount of active power is lost when current flows through power grids due to the resistance of transmission equipment. During a given period (day, month, season, or year), the total active power consumed by various grid equipment is called grid losses. This generally includes the active power consumed by transmission equipment (referred to as line losses) and the active power consumed by transformers (referred to as transformer losses). For grid companies that manage power transmission, such as provincial and municipal grid companies, while the grids are physically connected, each grid company's jurisdiction is only a portion of the overall network, divided either by region or by voltage level. Clear boundaries define the boundaries between the grid equipment under each grid company's jurisdiction. Similarly, the grid equipment managed by grid companies and power generation companies also has clear boundaries. When calculating active power losses, each grid company only counts the losses incurred by equipment within its jurisdiction during power transmission.

[0005] Based on the calculation method, power grid losses can be divided into two categories: statistical losses and theoretical losses. Statistical losses are calculated based on the readings on the electricity meter and are the difference between the total inflow (i.e., online electricity) and outflow (i.e., offline electricity) of the power grid involved in the statistical calculation of power losses within a given time period. Theoretical losses are calculated based on the known grid structure and operating parameters, using electrical engineering principles and theories in electrical engineering to calculate the voltage, current, and corresponding power loss of each transmission device within the jurisdiction. The resulting loss is called theoretical loss, and the theoretical loss of the power grid is the sum of the theoretical losses of all electrical equipment within the jurisdiction.

[0006] Power system flow calculations study the steady-state operation of a power system. Based on given data, they calculate busbar voltages, component power, and network losses, and assess the operational status of various parts of the power grid. This calculated data is then used to monitor and optimize the operation of the power grid system, thereby improving the rationality, reliability, and economic efficiency of the power supply plan or operating mode. For an operating power system, flow calculations can assess whether parameters such as busbar voltages and branch power are exceeding their limits. If anomalies are detected, measures should be taken to adjust the operating mode.

[0007] Specifically, the power flow equation in polar coordinates can be expressed as:

[0008]

[0009] Among them, V i is the voltage amplitude of busbar i, θ i is the phase angle of bus voltage, V j is the voltage amplitude of busbar j, θ jis the phase angle of busbar j voltage, θ ij is the phase angle difference between busbar i and busbar j, I represents the set of busbars j connected to busbar i through branches; G ij is the conductance of the branch connecting busbars i and j, B ij is the susceptance connecting busbar i and busbar j. Gi is the active power generation on bus i, P Di is the active load on bus i, Q Gi is the reactive power generation of busbar i, Q Di is the reactive load on bus i.

[0010] From the above power flow equation, we can further obtain the branch power flow calculation expression as follows:

[0011]

[0012] Among them, P ij 、P ji is the active power flow P flowing on the branch connecting busbar i and its adjacent busbar j ij P represents the branch active power flow from bus i to bus j, ji It represents the branch active power flow from bus j to bus i; the branch includes the line or transformer winding connected to the bus. ij is the branch reactive power flow from busbar i to busbar j, y c Represents the semi-admittance of the line.

[0013] Power flow calculations can determine the steady-state operating state of a power grid when the grid structure parameters are determined. Nodes in the power grid can be divided into PQ nodes, PV nodes, and Vθ nodes based on given variables. The grid state variables to be calculated are the node voltage amplitudes and phase angles. The power flow equations are a set of high-order nonlinear algebraic equations that must be solved using an iterative method. The Newton-Raphson power flow algorithm is a power flow algorithm with second-order convergence and is therefore widely used. However, since the Jacobian matrix of this method is a function of the state variables to be determined, the Jacobian matrix must be reformed and solved using the Gaussian elimination method during the iteration process, resulting in a high amount of computational effort for each iteration. As it forms the basis of various power flow calculation methods, it plays an important role in power grid analysis.

[0014] Grid loss calculation is a complex component of power system flow calculations. Traditional grid loss optimization systems require manual specification of various sensitivity calculation schemes, followed by the selection of loss reduction schemes guided by the analyst's experience. Due to the complex topology of the transmission network and the large amount of data, the resulting sensitivity scheme state space grows exponentially, significantly reducing analyst efficiency.

[0015] After an automatic voltage control system (AVC) is put into closed-loop operation, it remains in a continuous closed-loop control state. Each round of control strategy is based on the grid state after the previous round of control strategy execution. Therefore, the reduction in active power loss in the transmission network caused by AVC is a cumulative result over a continuous period of time, making accurate calculation difficult. Furthermore, after AVC is put into closed-loop control, it is impossible to arbitrarily exit closed-loop control for comparative analysis. Therefore, quantitative analysis of the actual reduction in active power loss in the transmission network caused by a closed-loop AVC system has always been a challenge. Operations and maintenance personnel need to analyze the various factors affecting AVC operation and provide recommendations for improvements based on the quantitative calculation results of active power loss reduction generated by AVC closed-loop control. With the widespread adoption of AVC systems at all levels of transmission networks in China, the need for quantitative analysis of the reduction in active power loss in the transmission network caused by AVC is becoming increasingly urgent. However, no relevant calculation methods or research results have been reported in this area, either domestically or internationally. Summary of the Invention

[0016] The present invention aims to overcome the shortcomings of existing technologies by proposing a sensitivity-based method for calculating the active power loss caused by automatic voltage control in the power grid. This method provides online, real-time quantitative calculation results of the active power loss caused by automatic voltage control after the automatic voltage control system is put into closed-loop operation, contributing to the safe and efficient operation of the power grid.

[0017] An embodiment of the present invention provides a method for calculating active power loss in a power grid caused by automatic voltage control based on sensitivity, including:

[0018] When the current automatic voltage control cycle arrives, a set of reactive devices that affect active power loss in the power grid is obtained;

[0019] Calculating the sensitivity of the reactive output of each reactive device in the reactive device set to the active power flow loss of the power grid; obtaining the reactive output change of each reactive device in the reactive device set during the current automatic voltage control cycle;

[0020] Calculating the active power flow loss of the power grid caused by the reactive equipment based on the sensitivity and the reactive power output change;

[0021] Based on the active power flow loss of the power grid caused by the reactive equipment, the rectangular method is used for integration to calculate the active power loss of the power grid caused by the reactive equipment in the current automatic voltage control period.

[0022] In a specific embodiment of the present invention, obtaining a set of reactive devices that affect active power loss in a power grid includes:

[0023] 1) Obtain the set S of reactive devices that affect the active power loss of the power grid saved at the end of the previous automatic voltage control cycle aand the set of duration periods that affect the active power loss of the power grid T a , where the set S a Contains the reactive devices that affect the active power loss of the power grid saved in the previous automatic voltage control cycle, set T a Contains S a The duration period of each reactive device affecting the active power loss of the power grid;

[0024] 2) The arrival time of the current automatic voltage control cycle is t0; at t0, the automatic voltage control system sends the controlled reactive power to the controlled reactive power device Dev. m When issuing a control instruction, determine:

[0025] like Then the controlled reactive device Dev m Add to collection S a ; The controlled reactive equipment Dev m The duration of the period that affects the active power loss of the power grid Add to collection T a , where T s T is the duration of the preset controlled reactive equipment affecting the active power loss of the grid, s It is an integer multiple of the automatic voltage control cycle length;

[0026] If Dev m ∈S a , then the set S a Do not update, update set T a Mid-Dev m The duration of the period that affects the active power loss of the power grid make Dev m is the mth controlled reactive device;

[0027] 3) After the controlled reactive equipment that receives the control instruction of the automatic voltage control system at time t0 is determined, the set T a All elements of are tested; if the set T a There is any reactive device Dev n The duration of the period that affects the active power loss of the power grid Then From the set T a Delete it and change Dev n From the set S a Delete, Dev n is the nth controlled reactive device;

[0028] After the test is completed, the set S of the current automatic voltage control period is obtained a and set T a .

[0029] In a specific embodiment of the present invention, it also includes:

[0030] Calculate the sensitivity of bus voltage to grid active power flow loss. The specific steps are as follows:

[0031] 1) Calculate the impact of the busbar on the active power flow loss of the power grid;

[0032] For any busbar i,

[0033]

[0034] Among them, P ij P represents the branch active power flow from bus i to bus j, ji represents the branch active power flow from bus j to bus i; represents the active power flow loss on the branch connecting busbar i and its adjacent busbar j, P i loss is the active power flow loss of all branches connected to busbar i;

[0035] 2) Based on the result of step 1), calculate the sensitivity of the bus voltage to the active power flow loss of the grid;

[0036] Among them, the sensitivity of the voltage of any bus i to the active power flow loss of the power grid is:

[0037]

[0038] Among them, V i is the voltage amplitude of busbar i, θ i is the phase angle of busbar i voltage, Calculate the partial derivative of the active power flow loss of all branches connected to bus i with respect to the amplitude of bus i voltage, Calculate the partial derivative of the active power flow loss of all branches connected to bus i with respect to the phase angle of bus i voltage;

[0039] According to the branch power flow equation, we get:

[0040]

[0041] Among them, V j is the voltage amplitude of busbar j, g ij is the conductance of the branch connecting busbars i and j, b ij is the susceptance of the branch, θ ij is the phase angle difference between busbar i and busbar j;

[0042] From equations (3)-(6), we can get:

[0043]

[0044] The V calculated by the current power grid flow i 、V j and θ ij Substituting into equations (7) and (8), we can obtain the sensitivity of the voltage of bus i to the active power flow loss of the power grid.

[0045] In a specific embodiment of the present invention, it also includes:

[0046] 1) Calculate the sensitivity of reactive output of reactive devices in the set of reactive devices that affect active power loss in the power grid to the bus voltage;

[0047] Among them, the linearized power flow correction equation is:

[0048]

[0049] Where [J] is the constant Jacobian matrix, Δθ is the voltage phase angle change matrix, ΔU is the voltage amplitude change matrix, ΔP is the active power change matrix, and ΔQ is the reactive power change matrix;

[0050] When calculating the sensitivity of reactive output of reactive devices in the set of reactive devices that affect the active power loss of the power grid to the voltage of each busbar of the power grid, the reactive output of any reactive device in the set Dev k Connected to busbar l, the right side vector of equation (9) is set to: where ΔQ l =1,ΔQ l Indicates the change in injected reactive power on the lth bus;

[0051] Solve equation (9) to get the reactive device Dev k The sensitivity of reactive power to the voltage phase angle of any bus i in the grid is Δθ i And the reactive device Dev k Sensitivity ΔU of reactive power to voltage amplitude of busbar i in the power grid i , thus obtaining the controlled reactive device Dev k The sensitivity matrix of reactive power to the phase angle of all bus voltages in the power grid is Δθ = {Δθ1...Δθ i ...Δθ M}, 1≤i≤M and the sensitivity matrix of the reactive output of the controlled reactive device k to the voltage amplitude of all buses in the power grid ΔU={ΔU1...ΔU i ...ΔU M},1≤i≤M, where the subscript i corresponds to the busbars included in the power grid and M is the number of busbars;

[0052] 2) Calculate the sensitivity of the reactive output of reactive devices in the set of reactive devices that affect the active power loss of the power grid to the active power flow loss of the power grid;

[0053] Among them, any reactive device Dev k The sensitivity of reactive output to active power flow loss of the power grid is:

[0054]

[0055] In a specific embodiment of the present invention, it also includes:

[0056] If the reactive device Dev in the reactive device set that affects the active power loss of the power grid k Cp is a low voltage capacitor or reactor k , then the reactive output change of the reactive equipment from the arrival time t0 to the end time t1 of the current automatic voltage control cycle is the reactive capacity of the low-voltage capacitor or reactor, that is where ΔQ k For reactive equipment Dev k The reactive output change, Cp is a low voltage capacitor or reactor k Reactive capacity;

[0057] If the reactive device Dev k For the generator Un k , then the reactive output change of the reactive equipment from the arrival time t0 to the end time t1 of the current automatic voltage control cycle is the reactive output change of the generator, that is The generator Un at time t1 k The reactive power output, is the generator Un at time t0 k Reactive output.

[0058] In a specific embodiment of the present invention, it also includes:

[0059] Any reactive device Dev k The active power flow loss of the power grid caused by this is:

[0060]

[0061] in, For reactive equipment Dev k The active power flow loss caused by the power grid.

[0062] In a specific embodiment of the present invention, it also includes:

[0063] Use the rectangular method to perform integration and calculate the reactive device Dev in the reactive device set that affects the active power loss of the power grid k Active power loss caused by the grid

[0064]

[0065] The active power loss of the grid caused by all controlled reactive devices in the current automatic voltage control cycle is:

[0066]

[0067] Where W is the total number of reactive devices in the reactive device set that affects the active power loss of the power grid in the current control period.

[0068] In a specific embodiment of the present invention, it also includes:

[0069] At the end of the current automatic voltage control cycle, the set T s Reactive equipment Dev k The duration of the period that affects the active power loss of the power grid Updated to

[0070] The characteristics and beneficial effects of the present invention are:

[0071] The present invention calculates the impact of controlled reactive devices under automatic voltage control on grid losses based on the sensitivity of the reactive output of controlled reactive devices to the active power flow loss of the grid. It also introduces the period of the impact of controlled reactive devices on grid losses, flexibly controls the time of their impact on grid losses, and ultimately calculates the loss of active power in the grid caused by the control strategy issued under each automatic voltage control cycle after the reactive devices are activated. The present invention can calculate the quantitative calculation results of the active power loss of the grid caused by automatic voltage control in real time after the automatic voltage control system is put into closed-loop operation. Operation and maintenance personnel need to analyze the various factors affecting the operation of the automatic voltage control and provide improvement suggestions based on the quantitative calculation results of the active power loss generated by the automatic voltage control closed-loop control, thereby achieving the purpose of reducing grid losses. The present invention can be applied to the automated dispatching reactive voltage control systems of various provincial and regional power grids to quantitatively calculate the active power loss caused by automatic voltage control in various regions, contributing to the safe and efficient operation of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 The present invention is a flowchart of a method for calculating active power loss of a power grid caused by automatic voltage control based on sensitivity calculation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0073] The present invention proposes a method for calculating active power loss in a power grid caused by automatic voltage control based on sensitivity calculation, which is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0074] An embodiment of the present invention provides a method for calculating active power loss in a power grid caused by automatic voltage control based on sensitivity, including:

[0075] When the current automatic voltage control cycle arrives, a set of reactive devices that affect active power loss in the power grid is obtained;

[0076] Calculating the sensitivity of the reactive output of each reactive device in the reactive device set to the active power flow loss of the power grid; obtaining the reactive output change of each reactive device in the reactive device set during the current automatic voltage control cycle;

[0077] Calculating the active power flow loss of the power grid caused by the reactive equipment based on the sensitivity and the reactive power output change;

[0078] Based on the active power flow loss of the power grid caused by the reactive equipment, the rectangular method is used for integration to calculate the active power loss of the power grid caused by the reactive equipment in the current automatic voltage control period.

[0079] In a specific embodiment of the present invention, the method for calculating the active power loss of the power grid caused by automatic voltage control based on sensitivity calculation has the following overall process: Figure 1 As shown, the following steps are included:

[0080] 1) Set the automatic voltage control cycle length to T c , set the duration of the controlled reactive equipment affecting the active power loss of the grid to T s , T s T c K times, where K ≥ 1 is an integer.

[0081] 2) When the current automatic voltage control cycle arrives, the arrival time is recorded as t0, and the grid section model is read from the dispatching and monitoring system of the power grid dispatching center; based on the information of the controlled reactive devices that receive the control instructions of the automatic voltage control system at time t0, the set of reactive devices that affect the active power loss of the grid in the current automatic voltage control cycle is obtained.

[0082] In this embodiment, the power grid section model includes: the transmission network topology, electrical parameters of the primary equipment of the transmission network, active power and reactive power of the power plant generator, active power and reactive power of the equivalent load, and the open and closed states of the transmission network circuit breakers and disconnecting switches.

[0083] The controlled reactive equipment includes: a power plant generator, a low-voltage capacitor and a low-voltage reactor.

[0084] The specific steps for obtaining the set of reactive devices that affect the active power loss of the power grid in the current period are as follows:

[0085] 2-1) Obtain the set S of reactive devices that affect the active power loss of the power grid saved at the end of the previous automatic voltage control cycle a and the set of duration periods that affect the active power loss of the power grid T a , where the set S aContains the reactive devices that affect the active power loss of the power grid saved in the previous automatic voltage control cycle, set T a Contains S a The duration of each reactive device affecting the active power loss of the power grid. a and set T a Initially all are empty.

[0086] 2-2) At time t0, the automatic voltage control system sends the controlled reactive power to the controlled reactive power device Dev m When issuing a control instruction, determine:

[0087] like Then the controlled reactive device Dev m Add to collection S a ; The controlled reactive equipment Dev m The duration of the period that affects the active power loss of the power grid Add to collection T a ,make Among them

[0088] If Dev m ∈S a , it means that the controlled reactive device Dev m Already in collection S a In the set S a Do not update, update set T a Mid-Dev m The duration of the period that affects the active power loss of the power grid make Dev m is the mth controlled reactive device.

[0089] 2-3) After the controlled reactive equipment that receives the control instruction of the automatic voltage control system at time t0 is determined, the set T a All elements of are tested; if the set T a There is any reactive device Dev n The duration of the period that affects the active power loss of the power grid Then From the set T a Delete it and change Dev n From the set S a Delete, Dev n is the nth controlled reactive device.

[0090] After the inspection, the set S a and set T a Update completed, save the current automatic voltage control cycle set S a and set T a .

[0091] 3) Based on the results of step 2), calculate the sensitivity of the bus voltage to the active power flow loss of the grid; the specific steps are as follows:

[0092] 3-1) Calculate the impact of the busbar on the active power flow loss of the power grid.

[0093] In this embodiment, the impact of any busbar i on the active power flow loss of the power grid is mainly manifested as the network loss of the branch connected to the busbar, which can be expressed as:

[0094]

[0095] Among them, P ij 、P ji is the active power flow on the branch connecting busbar i and its adjacent busbar j, P ij P represents the branch active power flow from bus i to bus j, ji represents the branch active power flow from busbar j to busbar j; represents the active power flow loss on the branch connecting busbar i and its adjacent busbar j, P i loss is the active power flow loss of all branches connected to busbar i.

[0096] 3-2) Based on the result of step 3-1), calculate the sensitivity of the bus voltage to the grid active power flow loss.

[0097] In this embodiment, based on the result of step 3-1), the sensitivity of the voltage of bus i to the active power flow loss of the power grid is:

[0098]

[0099] Among them, V i is the voltage amplitude of busbar i, θ i is the phase angle of busbar i voltage, Calculate the partial derivative of the active power flow loss of all branches connected to bus i with respect to the amplitude of bus i voltage, Obtain the partial derivative of the active power flow loss of all branches connected to bus i with respect to the phase angle of the bus i voltage.

[0100] According to the branch flow equation, we can get:

[0101]

[0102]

[0103] Among them, V j is the voltage amplitude of busbar j, g ij is the conductance of the branch connecting busbars i and j, bij is the susceptance of the branch, θ ij is the phase angle difference between busbars i and j.

[0104] From formulas (3)-(6), we can get:

[0105]

[0106] Equations (7) and (8) give the sensitivity of the voltage (amplitude and phase angle) of bus i to the active power flow loss of the power grid. In the calculation, the V i 、V j and θ ij Substituting into equations (7) and (8), we can obtain the sensitivity of the voltage of bus i to the active power flow loss of the power grid in the current state.

[0107] 4) Based on the result of step 2), the sensitivity of the reactive output of each reactive device in the set of reactive devices that affect the active power loss of the power grid in the current cycle to the active power flow loss of the power grid is calculated; the specific steps are as follows:

[0108] 4-1) Calculate the sensitivity of the reactive output of the reactive devices in the set of reactive devices that affect the active power loss of the power grid to the bus voltage.

[0109] In this embodiment, according to Zhang Boming, Chen Shousun, et al. in Advanced Power Network Analysis (Tsinghua University Press, 1996, pp. 190-191), in the Newton method power flow calculation, the linearized power flow correction equation can be written as:

[0110]

[0111] Where [J] is the constant Jacobian matrix, Δθ is the voltage phase angle change matrix, ΔU is the voltage amplitude change matrix, ΔP is the active power change matrix, and ΔQ is the reactive power change matrix.

[0112] The Jacobian matrix describes the effect of injected active and reactive power on the bus voltage. Using the current power flow calculation results to form a constant Jacobian matrix, a linear equation is constructed as shown in Equation (9) showing the change in injected power flow and the change in bus voltage.

[0113] When calculating the sensitivity of reactive output of reactive devices in the set of reactive devices that affect the active power loss of the power grid to the voltage of each busbar of the power grid, assume that any reactive device Dev in the set k Connected to busbar l, the right side vector of equation (9) is set to: where ΔQ l =1,ΔQ lIt represents the change of reactive power injected on the l-th bus. That is, except for the reactive power injected on the l-th bus, which has a unit change, its change is the reactive power flow growth unit 1, and the reactive power injected on other buses is 0. Solving formula (9), we can get the reactive power device Dev k The sensitivity of reactive power to the voltage phase angle of any bus i in the grid is Δθ i And the reactive device Dev k Sensitivity ΔU of reactive power to voltage amplitude of busbar i in the power grid i , thus obtaining the controlled reactive device Dev k The sensitivity matrix of reactive power to the phase angle of all bus voltages in the power grid is Δθ = {Δθ1...Δθ i ...Δθ M}, 1≤i≤M and the sensitivity matrix of the reactive output of the controlled reactive device k to the voltage amplitude of all buses in the power grid ΔU={ΔU1...ΔU i ...ΔU M},1≤i≤M, where the subscript i corresponds to the busbars included in the power grid and M is the number of busbars.

[0114] 4-2) Based on the results of steps 3) and 4-1), the sensitivity of the reactive output of the reactive devices in the set of reactive devices that affect the active power loss of the power grid to the active power flow loss of the power grid is calculated.

[0115] In this embodiment, any reactive device Dev k The sensitivity of reactive output to active power flow loss of the power grid is:

[0116]

[0117] 5) Obtain the reactive output change of each reactive device in the reactive device set that affects the active power loss of the power grid during the current automatic voltage control cycle.

[0118] In this embodiment, if the reactive device Dev in the reactive device set that affects the active power loss of the power grid k Cp is a low voltage capacitor or reactor k , then the reactive output change of the reactive equipment from the arrival time t0 to the end time t1 of the current automatic voltage control cycle is the reactive capacity of the low-voltage capacitor or reactor, that is where ΔQ k For reactive equipment Dev k The reactive output change, Cp is a low voltage capacitor or reactor k Reactive capacity;

[0119] If the reactive device Dev in the reactive device set that affects the active power loss of the power grid k For the generator Un k, then the reactive output change of the reactive equipment from the arrival time t0 to the end time t1 of the current automatic voltage control cycle is the reactive output change of the generator, that is The generator Un at time t1 k The reactive power output, is the generator Un at time t0 k Reactive output.

[0120] 6) Based on the results of steps 4) and 5), the grid active power flow loss caused by each reactive device in the reactive device set that affects the grid active power loss in the current control period is calculated.

[0121] Among them, any reactive device Dev k The active power flow loss of the power grid caused by this is:

[0122]

[0123] in, For reactive equipment Dev k The active power flow loss caused by the power grid.

[0124] 7) Based on the result of step 6), the rectangular method is used for integration to obtain the active power loss of the power grid caused by all controlled reactive devices in the current automatic voltage control period.

[0125] Among them, the rectangular method is used for integration to calculate the reactive equipment Dev in the reactive equipment set that affects the active power loss of the power grid. k Active power loss caused by the grid

[0126]

[0127] The active power loss of the grid caused by all controlled reactive devices in the current automatic voltage control cycle is:

[0128]

[0129] Where W is the total number of reactive devices in the reactive device set that affects the active power loss of the power grid in the current control period.

[0130] 8) At the end of the current automatic voltage control cycle, the set T s Reactive equipment Dev k The duration of the period that affects the active power loss of the power grid Updated to

[0131] 9) At time t1 when the next automatic voltage control cycle arrives, record t1 as the new t0 and return to step 2).

Claims

1. A method for calculating active power loss of a power grid caused by automatic voltage control based on sensitivity, characterized in that: include: When the current automatic voltage control cycle arrives, the set of reactive devices that affect the active power loss of the power grid is obtained; Calculating the sensitivity of the reactive output of each reactive device in the reactive device set to the active power flow loss of the power grid; obtaining the reactive output change of each reactive device in the reactive device set during the current automatic voltage control cycle; Calculating the active power flow loss of the power grid caused by the reactive equipment based on the sensitivity and the reactive output change; Based on the active power flow loss of the power grid caused by the reactive equipment, the rectangular method is used for integration to calculate the active power loss of the power grid caused by the reactive equipment in the current automatic voltage control period.

2. The method according to claim 1, characterized in that The step of obtaining a set of reactive devices that affect active power loss in a power grid includes: 1) Obtain the set of reactive devices that affect the active power loss of the power grid saved at the end of the previous automatic voltage control cycle S a and the set of continuous periods that affect the active power loss of the power grid T a , where the set S a Contains the reactive devices that affect the active power loss of the power grid saved in the previous automatic voltage control cycle, set T a Contains S a The duration period of each reactive device affecting the active power loss of the power grid; 2) The arrival time of the current automatic voltage control cycle is t0; at t0, the automatic voltage control system sends the controlled reactive power to the controlled reactive power device Dev. m When issuing a control instruction, determine: like Then the controlled reactive device Dev m Add to collection S a ; The controlled reactive equipment Dev m The duration of the period that affects the active power loss of the power grid Add to collection T a , where T s T is the duration of the preset controlled reactive equipment affecting the active power loss of the grid, s It is an integer multiple of the automatic voltage control cycle length; If Dev m ∈S a , then the set S a Do not update, update set T a Mid-Dev m The duration of the period that affects the active power loss of the power grid make Dev m is the mth controlled reactive device; 3) After the controlled reactive equipment that receives the control instruction of the automatic voltage control system at time t0 is determined, the set T a All elements of are tested; if the set T a There is any reactive device Dev n The duration of the period that affects the active power loss of the power grid Then From the set T a Delete it and change Dev n From the set S a Delete, Dev n is the nth controlled reactive device; After the test is completed, the set S of the current automatic voltage control period is obtained a and set T a .

3. The method according to claim 2, characterized in that Also includes: Calculate the sensitivity of bus voltage to grid active power flow loss. The specific steps are as follows: 1) Calculate the impact of the busbar on the active power flow loss of the power grid; For any busbar i, Among them, P ij P represents the branch active power flow from bus i to bus j, ji represents the branch active power flow from bus j to bus i; represents the active power flow loss on the branch connecting busbar i and its adjacent busbar j, P i loss is the active power flow loss of all branches connected to busbar i; 2) Based on the result of step 1), calculate the sensitivity of the bus voltage to the active power flow loss of the grid; Among them, the sensitivity of the voltage of any bus i to the active power flow loss of the power grid is: Among them, V i is the voltage amplitude of busbar i, θ i is the phase angle of busbar i voltage, Calculate the partial derivative of the active power flow loss of all branches connected to bus i with respect to the amplitude of bus i voltage, Calculate the partial derivative of the active power flow loss of all branches connected to bus i with respect to the phase angle of bus i voltage; According to the branch power flow equation, we get: Among them, V j is the voltage amplitude of busbar j, g ij is the conductance of the branch connecting busbars i and j, b ij is the susceptance of the branch, θ ij is the phase angle difference between busbar i and busbar j; From equations (3)-(6), we can get: The V calculated by the current power grid flow i 、V j and θ ij Substituting into equations (7) and (8), we can obtain the sensitivity of the voltage of bus i to the active power flow loss of the grid.

4. The method according to claim 3, characterized in that Also includes: 1) Calculate the sensitivity of reactive output of reactive devices in the set of reactive devices that affect active power loss in the power grid to the bus voltage; Among them, the linearized power flow correction equation is: Where [J] is the constant Jacobian matrix, Δθ is the voltage phase angle change matrix, ΔU is the voltage amplitude change matrix, ΔP is the active power change matrix, and ΔQ is the reactive power change matrix; When calculating the sensitivity of reactive output of reactive devices in the set of reactive devices that affect the active power loss of the power grid to the voltage of each busbar of the power grid, the reactive output of any reactive device in the set Dev k Connected to busbar l, the right side vector of equation (9) is set to: where ΔQ l =1,ΔQ l Indicates the change in injected reactive power on the lth bus; Solve equation (9) to get the reactive device Dev k The sensitivity of reactive power to the voltage phase angle of any bus i in the grid is Δθ i And the reactive device Dev k Sensitivity ΔU of reactive power to voltage amplitude of busbar i in the power grid i , thus obtaining the controlled reactive device Dev k The sensitivity matrix of reactive power to the phase angle of all bus voltages in the power grid is Δθ = {Δθ1...Δθ i ...Δθ M }, 1≤i≤M and the sensitivity matrix of the reactive output of the controlled reactive device k to the voltage amplitude of all buses in the power grid ΔU={ΔU1...ΔU i ...ΔU M },1≤i≤M, where the subscript i corresponds to the busbars included in the power grid and M is the number of busbars; 2) Calculate the sensitivity of the reactive output of the reactive devices in the set of reactive devices that affect the active power loss of the power grid to the active power flow loss of the power grid; Among them, any reactive device Dev k The sensitivity of reactive output to active power flow loss of the power grid is:

5. The method according to claim 4, characterized in that Also includes: If the reactive device Dev in the reactive device set that affects the active power loss of the power grid k Cp is a low voltage capacitor or reactor k , then the reactive output change of the reactive equipment from the arrival time t0 to the end time t1 of the current automatic voltage control cycle is the reactive capacity of the low-voltage capacitor or reactor, that is where ΔQ k For reactive equipment Dev k The reactive output change, Cp is a low voltage capacitor or reactor k Reactive capacity; If the reactive device Dev k For the generator Un k , then the reactive output change of the reactive equipment from the arrival time t0 to the end time t1 of the current automatic voltage control cycle is the reactive output change of the generator, that is The generator Un at time t1 k The reactive power output, is the generator Un at time t0 k Reactive output.

6. The method according to claim 5, characterized in that Also includes: Any reactive device Dev k The active power flow loss of the power grid caused by this is: in, For reactive equipment Dev k The active power flow loss caused by the power grid.

7. The method according to claim 6, characterized in that Also includes: Use the rectangular method to perform integration and calculate the reactive device Dev in the reactive device set that affects the active power loss of the power grid k Active power loss caused by the grid The active power loss of the grid caused by all controlled reactive devices in the current automatic voltage control cycle is: Where W is the total number of reactive devices in the reactive device set that affects the active power loss of the power grid in the current control period.

8. The method according to claim 7, characterized in that Also includes: At the end of the current automatic voltage control cycle, the set T s Reactive equipment Dev k The duration of the period that affects the active power loss of the power grid Updated to

Images